The PRC has a H2O capacity of 72g, the 264WM has a H2O case capacity of 83g.
This tells me, with the correct twist of 8" or faster, the 264WM will win the race with heavy projectiles.
With a 9" twist the 264WM is limited to about 142g bullets….so the PRC wins with heavy for calibre bullets only in the fact that it comes standard with a faster twist, but it is not faster than the 264WM if both have the same twist.
My own 264WM has a 8" twist in a 29" barrel. It will punish any PRC even with a longer barrel due to my throat dimensions.
Cheers.